Magnetic security switches use the detection of a magnetic field, or loss of detection of a magnetic field, to indicate that a door, window or other enclosure access has been opened. In its simplest form, a magnetic security switch uses permanent magnet (referred to herein as a “target magnet”) mounted to an enclosure access, e.g. a door to a room, and a magnetic sensor, such as a reed switch, acting as a switch to detect the presence or absence of the target magnet. If the magnet is detected, then the door is in the expected position. If no magnet is detected, then the door is not in the expected position. This go/no-go signal can be used as an input to an alarm system, automatic monitoring systems, or safety interlocks.
The effectiveness of the security switch is directly affected by the alignment of the target magnet to the detector switch when the door is in the expected position—if the target magnet is not within the detector switch's reliable detection range when the door is in the expected position then the detector switch will incorrectly indicate that the door is not in position. The converse is also true—a misaligned target magnet may inadvertently be within the detection range of the detector switch when the door is not in the expected position and therefore incorrectly indicate that the door is in position (e.g. a partially closed door indicated as fully closed).
External mounting of target magnets leaves them vulnerable to tampering, therefore it is preferable to mount the target magnet inside the door itself. Generally, a U-channel is formed into or machined into a door edge and the target magnet is mounted inside this U-channel. Existing devices for mounting target magnets into door U-channels involve either screwing mounting brackets into the U-channel, or using adhesives such as epoxy to permanently set the target magnet in place. Adjustments to ensure proper alignment with the detector switch are labor intensive and therefore expensive, and generally the installation location is essentially permanent—especially where adhesives are used. Subsequent modifications to the mounting location are equally labor intensive, and may require destructive removal of the target magnet. For installations in secure buildings, where hundreds of doors and windows may require magnetic security switches, even small improvements in the time and skill required for installation will yield substantial cost savings.
Thus, there is a need for a target magnet mounting system which is: (1) quick to install; (2) easily aligned; (3) inexpensive to manufacture; (4) easily changed; and (5) compatible with existing security switch systems.